IBM 890 manual Parallel Sysplex Coupling Connectivity, Route A, Route B

Parallel Sysplex Coupling Connectivity

The Coupling Facilities communicate with z/OS images in the Parallel Sysplex environment over specialized high-speed links. For availability purposes, it is recom- mended that there be at least two links connecting each z/OS image to each CF in a Parallel Sysplex cluster. As processor performance increases, it is important to also use faster links so that link performance does not become constrained. The performance, availability and distance requirements of a Parallel Sysplex environment are the key factors that will identify the appropriate connectivity option for a given confi guration.

Parallel Sysplex Coupling Links on the zSeries have been enhanced with the introduction of Peer Mode. When con- necting between zSeries servers, the links can be confi g- ured to operate in Peer Mode. This allows for higher data transfer rates to and from the Coupling Facilities. In Peer Mode, the fi ber optic single mode coupling link (ISC-3) provides 200 Gbps capacity, up to 12 km, 100 Gbps up to 20 km, the ICB-3 link with 1 GB/s peak capacity, the ICB-4 supported on z890s and z990s connection at 2.0 GBps, and the IC-3 link with 3.5 GBps capacity. Additional Peer Mode benefi ts are obtained by enabling the link to be MIFed between z/OS (or OS/390) and CF LPARs. The peer link acts simultaneously as both a CF Sender and CF Receiver link, reducing the number of links required. Larger and more data buffers and improved protocols also improve long distance performance. For connectiv- ity to 9672s, zSeries ISC-3 CF links can be confi gured to run in Compatibility Mode with the same characteristics as links on the 9672 of 100 Gbps. The ICB coupling link speeds described above are theoretical maximums. Note: The z890 does not support ICB-2 links for connectivity to 9672s. ISC-3 links in compatibility mode must be used.

GDPS/PPRC Cross Site Parallel Sysplex distance Extended to

100 km

When using a Dense Wave Division Multiplexer (DWDM), it will be possible via an RPQ to confi gure GDPS/PPRC or a multi-site Parallel Sysplex with up to 100 km between the two sites. The immediate advantage of this extended distance is to potentially decrease the risk that the same disaster will affect both sites, thus providing the ability for customers to recover their production applications at another site. Support for the External Timer Reference (ETR) links and the Inter System Channel (ISC-3) links has been increased from the current capability of 50 km to an extended capability of up to 100 km. The extended distance support for ETR and ISC-3 links is now consis- tent with other cross site technologies that already sup- port 100 km (such as FICON, Peer-to-Peer Remote Copy (PPRC), and Peer-to-Peer Virtual Tape Server (PtP VTS)). It should be noted that the maximum distance between a pair of 9037 Sysplex Timers in an Expanded Availability confi guration remains at 40 km. Therefore, to achieve the extended distance of 100 km between the two sites, one of the options to be considered is locating one of the Sysplex Timers in an intermediary site that is less than 40 km from one of the two sites (as can be seen in the diagram below). Other potential options can be evaluated when the RPQ is ordered.

Site 1	up to	Site 2
	100 km

40 km max

40 km nom

9037

2 CLO

D

CLO

9037

D

CLO

D

links

D

11

12

W

11

12

1

W

1

10

2

10

2

3

W

8

4

W

9

D

9

3

D

8

4

D

7

6

5

1 ETR

D

7

6

5

M

M

ETR

M

1 ETR

ETR

ETR

link per

M

link per

CPC

ETR

CPC

ETR

Route A

D

D

ETR

ETR

W

W

D

D

M

1 ETR link

M

per CPC

CPC

hut with

CPC

amplifiers

Route B

Note: Midspan 9037 can also be located within 40 km of site 2 or on Route B. All ETR and CLO links are provisioned as 1 channel per wavelength.

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